Legislation of road vehicles was changed in Finland in 2013. The change allows the transport enterprises to get test licenses of specified time periods for vehicles, which exceed the limits of lengths and masses of the standard or normal vehicle combinations. The permanent legislation allows maximum gross mass of 76 t and length of 25.25 m for vehicles. The test vehicles (= HCT or High Capacity Transport vehicles) are mainly combinations with semi-trailers and/or trailers. So far (September 2017) number of these licences is more than 30. The Finnish Transport Agency (former Road Administration) ordered Vemosim Ltd to research the issue. The study includes driving resistance measurements of the HCT and standard vehicles. Based on these data fuel economy, carbon dioxide emissions and transportation costs are determined by simulation. Road wear impacts are determined, too. The interim conclusions are: the HCT vehicles are better than the normal vehicles in terms of fuel efficiency, CO2 emissions and of road wear impacts, provided that the roads are built according to the extant road design norms.